Relief in Sight from US Deep Freeze

Relief is on the way to the United States, which has seen days of life-threatening cold due to record low temperatures.

Temperatures are expected to rise to near normal in the Midwest by Thursday with spring-like weather expected in the East by the end of the week.

The end of the deep freeze will be welcomed by the airline industry, which had to cancel more than 11,000 flights over a four-day period. The Arctic conditions, which also disrupted train service and forced officials to shut down thousands of schools, has been blamed for at least 20 related deaths nationwide.

The bitter cold sent temperatures well below zero degrees Celsius in such midwestern cities as Chicago and Minneapolis spread to the East. It was minus 10 degrees Celsius Tuesday in Washington, New York, Philadelphia and Boston with the wind chill making it feel much colder.

Temperatures in all or parts of each of the 50 states were below freezing at some point Tuesday, in Hawaii it was minus six degrees Celsius on top of the Pacific state's highest mountain.

In the southern U.S., the federally-owned Tennessee Valley Authority, which provides power across seven Southern states, posted its second-highest winter demand as residents struggled to keep warm.

The frigid weather was caused by what meteorologists call a polar vortex, a rotating mass of cold dense air that usually stays in place in northern Canada, but was pushed south by the jet stream.